The invention relates to an apparatus and method for manufacturing devices for storing electric energy, in particular storage devices having a stack of cathodes and anodes that face one another alternatively with an interposed dielectric separator.
Specifically, but not exclusively, the invention may relate to the production of various types of storage devices—such as lithium batteries, electric double-layer capacitors, units for electrochemical treatment of liquids (for example oxygenators for water), electrostatic capacitors, fuel cells, etc—in which an electrode separator consists of a single continuous strip folded several times in the same folding direction.
Amongst known electric energy storage devices, lithium batteries are able to supply a relatively high voltage with an optimal energy-weight ratio. Various systems are known for manufacturing lithium batteries having a stack of flat cathodes and anodes that face one another alternatively and separated by a separator. In particular, producing a lithium battery with a separator consisting of a continuous single strip is known. In certain known manufacturing methods, adhesive means is used to join the electrodes to the separator, in particular on both the sides of a separating strip. In some embodiments forming the stack of electrodes by folding a separating strip several times in a zigzag is known; for example, using an apparatus is known that folds the strip in alternate directions (“z-folding”). A method is also known, for example from US 2006/0088759, for folding a separating strip in a single folding direction.
Patent publication WO 2002/095858 A1 shows an apparatus according to the preamble of claim 1. Patent publication WO 2003/100901 A1 shows a method according to the preamble of claim 14.
Systems known for manufacturing storage devices comprising a stack of electrodes that face one another and are separated by a separator consisting of a single continuous strip are improvable in various aspects.
In the first place, it is desirable to reduce the cost of manufacturing the storage device. Further, producing storage devices with relatively high capacity and performance is desirable. One of the drawbacks of assembling a stack of electrodes with the “z-folding” system is the reduced productivity. One of the drawbacks of the production of a storage device with a lamination system of the electrodes via adhesive means are the high costs (which are in particular due to the cost of the adhesive means) and the relatively low performance of the storage device (in particular because of the reduced ionic transfer between the electrochemical cells that is due to the adhesive means).